Hand tools such as screwdrivers and drills typically utilize a large number of bits of various sizes and configurations. For example, a screwdriver may utilize slotted, Phillips, hexagonal or star drive bits, and each different type of bit may come in various sizes. Similarly, power drill bits come in a wide variety of configurations and sizes for forming different sized holes in various different materials (e.g., different bits would normally be used for drilling in wood and in metal). It is inconvenient to store these different bits in a storage site that is separate from the hand tool due to the requirement to frequently access the storage site in order to change bits.
One solution to this problem is to store the bits within a storage compartment that is built into the hand tool itself, e.g., a compartment built into a drill casing or into the end of a screwdriver handle. Alternatively, slots or other cartridge systems may be attached to or formed on the body of the hand tool. However, such built-in storage compartments are often inconvenient to access, particularly when a user is at a work site (such as on a ladder) where it is difficult to gain access to the built in storage compartment. Even in those cases where the spare bits are easily accessible (such as when they are arrayed in circumferential grooves about a handle of a screwdriver) it may be difficult for a user to manually remove the bit from its stored location and then swap that bit with the one that is currently retained within a chuck or a bit holder of the hand tool.
Another solution to the above problems is to utilize a tool having an internal collection of bits that may be individually selected and moved to a working or distal end of the hand tool. Such solutions include providing a hollow shaft from the storage area to the distal end of the tool so that bits may be gravity fed directly from the storage area to a chuck or bit holder of the tool. Alternatively, a plurality of sliders may be provided within a body of the hand tool with a different bit attached to the end of each slider so that one slider/bit combination at a time may be extended through a distal opening of the tool. However, such solutions do not typically provide the ability to randomly change the bits that are internally stored within the hand tool. Rather, a selection of “popular” bits arc typically connected to the sliders, thus making such solutions inappropriate for those users that require a large variety of bit types and sizes.
A further solution is found in U.S. Pat. No. 4,572,038, entitled “Multi-Purpose Tool,” issued Feb. 25, 1986, to Charles Graham. This patent describes a hand tool having a retractable shaft with a distal end supporting an interchangeable bit, and further describes a cylinder holding a plurality of bits within different chambers of the cylinder. The shaft normally extends through one of the cylinder chambers when the distal end of the shaft is in an extended or operational position. However, when the distal end of the shaft is retracted through the chamber of the cylinder, the cylinder may be rotated to align a different chamber (and thus a different bit) with the distal end of the shaft. Once the distal end of the shaft is coupled with the new bit, the shaft is extended through the new cylinder chamber to its operational position. One drawback to this patented tool is that specialized bits are required for mating with the distal end of the retractable shaft. Specifically, each bit includes an arcuate tongue that is rotated into coupling engagement with an arcuate groove formed in the distal end of the shaft. This curved tongue and groove arrangement is necessary to allow the different bits to rotate into and out of engagement with the distal end of the shaft as the cylinder is rotated. Thus, this patented tool can not be used with traditional bits having a hexagonal base. Of course, the vast majority of replaceable screwdriver bits (as well as a large number of drill bits) include a hexagonal base for use with hexagonal drivers and other multi-bit screwdrivers having a hexagonal-shaped bit holder. Thus, users would be unable to use their existing (hexagonal-based) bits with this patented tool. A further drawback to the above-described patented tool is that each bit must rotate into and out of engagement with the distal end of the shaft as the cylinder is rotated. Due to this limitation, the hand tool is likely to bind as a user changes from a first bit to a second bit that is several chambers away from the first bit on the cylinder. Lastly, the patented tool is cumbersome to work with since the cylinder is offset from the axis of the retractable shaft. Thus, a user would have to separately hold the tool housing or the cylinder itself and then rotate the handle at the rear of the tool to drive the bit. Such operation is contrary to the normal operation of a manual screwdriver where the entire tool is typically rotated around the axis of the shaft and/or the bit itself.
Thus, an improved hand tool is needed that will allow a user to automatically change bits stored within the tool while simultaneously allowing the user to load the tool with standardized bits such as the hexagonal-based bits that are prevalent with prior art multi-bit hand tools. It is with respect to these and other background considerations, limitations and problems that the present invention has evolved.